WASHINGTON (Reuters) - U.S. commanders planning for the withdrawal of U.S. troops from Syria are recommending that Kurdish fighters battling Islamic State be allowed to keep U.S.-supplied weapons, four U.S. officials said, a move that would likely anger NATO ally Turkey.

Three of the officials, speaking on the condition of anonymity, said the recommendations were part of discussions on a draft plan by the U.S. military. It is unclear what the Pentagon will ultimately recommend to the White House.

Discussions are still at an early stage inside the Pentagon and no decision has yet been made, the officials said. The plan will then be presented to the White House in the coming days with U.S. President Donald Trump making the final decision.

The Pentagon said it would be "inappropriate" and premature to comment on what will happen with the weapons.

"Planning is ongoing, and focused on executing a deliberate and controlled withdrawal of forces while taking all measures possible to ensure our troops' safety," said Commander Sean Robertson, a Pentagon spokesman.The White House did not comment.

The U.S. officials said Trump's announcement has upset U.S. commanders, who view his decision as a betrayal of the Kurdish YPG militia, which has led the fight to eradicate Islamic State from northeastern Syria.

Ankara views the YPG as an extension of a Kurdish insurgency inside Turkey. Turkey has threatened to launch an offensive against the YPG, raising fears of a surge in violence that could harm hundreds of thousands of civilians.

The United States told the YPG that they would be armed by Washington until the fight against Islamic State was completed, one of the U.S. officials said.

"The fight isn't over. We can't simply start asking for the weapons back," said the official.

The proposal to leave U.S.-supplied weapons with the YPG, which could include anti-tank missiles, armoured vehicles and mortars, would reassure Kurdish allies that they were not being abandoned.

But Turkey wants the United States to take the weapons back, so the commanders' recommendation, if confirmed, could complicate Trump's plan to allow Turkey to finish off the fight against Islamic State inside Syria.

The Pentagon keeps records of the weapons it has supplied to the YPG and their chain of custody. But, the U.S. officials said, it would be nearly impossible to locate all of the equipment.

"How are we going to get them back and who is going to take them back?" one of the officials asked.

The debate over whether to leave weapons with the YPG coincides with Trump's national security adviser John Bolton's visit to Turkey and Israel next week for talks on Syria.

In May 2017, the United States started distributing arms and equipment to the YPG for an offensive against Raqqa, the de facto capital of the self-declared caliphate that Islamic State overran in Iraq and Syria in 2014.

The United States told Turkey that it would take back the weapons after the defeat of Islamic State, which has lost all but a few slivers of territory in northeastern Syria.

"The idea that we'd be able to recover them is asinine. So we leave them where they are," said a U.S. official.

A person familiar with the discussions of the U.S. withdrawal plan said the White House and Turkish President Tayyip Erdogan would oppose the proposal to allow the YPG to keep its U.S.-supplied weapons.

The recommendation "is a rejection of Trump's policy to withdraw from Syria," said the person, who asked not to be further identified.

Turkey has said weapons supplied to the YPG have in the past ended up in the hands of its Kurdish separatists, and described any weapon given to the insurgents as a threat to Turkey's security.

A phone call between Trump and Erdogan led to the decision to withdraw all U.S. forces from Syria.

In the call two weeks ago, Trump had been expected to deliver a standard warning to the Turkish president over his plan to launch a crossborder attack targeting U.S.-backed Kurdish forces in northeast Syria, U.S. officials said.

Instead, in the course of the conversation, Trump reshaped U.S. policy in the Middle East, abandoning a quarter of Syrian territory and handing Turkey the job of finishing off Islamic State in Syria.